Single-Component TiO2 Tubular Microengines with Motion Controlled by Light-Induced Bubbles

In this work, light-controlled bubble-propelled single-component metal oxide tubular microengines have for the first time been demonstrated. For such a simple single-component TiO2 tubular microengine in H2O2 aqueous solution under UV irradiation, when the inner diameter and length of the tube are regulated, the O-2 molecules will nucleate and grow into bubbles preferentially on the inner concave surface rather than on the outer surface, resulting in a vital propulsion of the microengine. More importantly, the motion state and speed can be modulated reversibly, fast (the response time is less than 0.2 s) and wirelessly by adjusting UV irradiation. Consequently, the as-developed TiO2 tubular microengine promises potential challenged applications related to photocatalysis, such as on-the-fly photocatalytic degradation of organic pollutes and photocatalytic inactivation of bacteria due to the low cost, single component, and simple structure, as well as the facile fabrication in a large-scale.